<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      function unique(arr) {
        return arr.filter((item, index, array) => {
          return array.indexOf(item) == index;
        });
      }
      console.log(unique([1, 2, 3, 4, 5, 1, 2, 3]));

      // es6实现
      var unique2 = (arr) => [...new set(arr)];
    </script>
  </body>
</html>
